<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        canvas{
            border:1px solid #ccc;
            margin-left:100px;
        }
        #c2{
            width:200px;
            height:200px;
        }
        #c3{
            width:600px;
            height: 600px;
        }
    </style>
</head>
<body>
    <style>
        canvas{
            border:1px solid #ccc;
            margin-left:100px;
        }
        #c2{
            width:200px;
            height:200px;
        }
        #c3{
            width:600px;
            height: 600px;
        }
    </style>
   <canvas id="c1" width="400" height="400"></canvas>
   <canvas id="c2" width="400" height="400"></canvas>
   <canvas id="c3" width="400" height="400"></canvas>

   <script>
    {
        const canvas= document.querySelector('#c1');
        const ctx = canvas.getContext('2d');
        ctx.fillRect(100,100,100,100);
    }

    {
        const canvas= document.querySelector('#c2');
        const ctx = canvas.getContext('2d');
        ctx.fillRect(100,100,100,100);
    }

    {
        const canvas= document.querySelector('#c3');
        const ctx = canvas.getContext('2d');
        ctx.fillRect(100,100,100,100);
    }
   </script>
</body>
</html>